Does it have to be online? I heard that the brand that jo-ann's (yes the fabric/craft) store carries is really good. They are almost the same price as the crocs, BUT you can use the coupon in the sunday paper to get 40 or 50% off... so it makes it a lot cheaper.
You could get some real ones pretty cheap right now at dicks sporting goods online. Right now there is free shipping, plus 15% off (just google dicks coupon codes) and if you sign up for google checkout you can get 10 dollars off your purchase.